UNIVERSITY  OF  CALIFORNIA  PUBLICATIONS 

COLLEGE  OF  AGRICULTURE 

AGRICULTURAL  EXPERIMENT  STATION 

BERKELEY,  CALIFORNIA 


GRAPE    SYRUP 

PRELIMINARY   REPORT 


BY 

FREDERIC  T.  BIOLETTI  and  W.  V.  CRUESS 


BULLETIN  No.  303 

January,  1919 


UNIVERSITY  OF  CALIFORNIA  PRESS 

BERKELEY 

1918 


Benjamin  Ide  Wheeler,  President  of  the  University. 

EXPERIMENT  STATION  STAFF 

HEADS    OF   DIVISIONS 

Thomas  Forsyth  Hunt,  Director. 

Edward  J.  Wickson,  Horticulture  (Emeritus). 

Herbert  J.  Webber,  Director  Citrus  Experiment  Station;  Plant  Breeding. 

Hubert  E.  Van  Norman,  Vice-Director;  Dairy  Management. 

William  A.  Setchell,  Botany. 

Myer  E.  Jaffa,  Nutrition. 

Charles  W.  Woodworth,  Entomology. 

Ralph  E.  Smith,  Plant  Pathology. 

J.  Eliot  Coit,  Citriculture. 

John  W.  Gilmore,  Agronomy. 

Charles  F.  Shaw,  Soil  Technology. 

John  W.  Gregg,  Landscape  Gardening  and  Floriculture. 

Frederic  T.  Bioletti,  Viticulture  and  Enology. 

Warren  T.  Clarke,  Agricultural  Extension. 

John  S.  Burd,  Agricultural  Chemistry. 

Charles.  B.  Lipman,  Soil  Chemistry  and  Bacteriology. 
t Clarence  M.  Haring,  Veterinary  Science  and  Bacteriology. 

Ernest  B.  Babcock,  Genetics. 

Gordon  H.  True,  Animal  Husbandry. 

James  T.  Barrett,  Plant  Pathology. 

Fritz  W.  Woll,  Animal  Nutrition. 

Walter  Mulford,  Forestry. 

W.  P.  Kelley,  Agricultural  Chemistry. 

H.  J.  Quayle,  Entomology. 

J.  B.  Davidson,  Agricultural  Engineering. 

Elwood  Mead,  Rural  Institutions. 

H.  S.  Reed,  Plant  Physiology. 

James  C.  Whitten,  Pomology, 
f  Frank  Adams,  Irrigation  Investigations. 

C.  L.  Roadhouse,  Dairy  Industry. 

Frederick  L.  Griffin,  Agricultural  Education. 

John  E.  Dougherty,  Poultry  Husbandry. 

S.  S.  Rogers,  Olericulture. 

R.  S.  Vaile,  Orchard  Management. 

J.  G.  Moodey,  Assistant  to  the  Director. 

Mrs.  D.  L.  Bunnell,  Librarian. 

DIVISION  OF  VITICULTURE 

Frederic  T.  Bioletti.  F.  C.  H.  Flossfeder. 

William  V.  Cruess.  A.  E.  Way. 

G.  Barovetto. 


t  In  military  service. 

t  In  co-operation  with   office  of  Public  Roads  and  Rural   Engineering,  U. 
Department  of  Agriculture. 


GRAPE   SYRUP 

PRELIMINARY   REPORT 

By  FREDERIC  T.  BIOLETTI  and  W.  V.  CRUESS 


I.     INTRODUCTION 

Sugar  in  Grapes. — Ripe  grapes,  especially  those  grown  in  Cali- 
fornia, are  so  sweet  that  their  use  as  a  source  of  sugar  is  naturally 
suggested.  Most  of  the  proposals  to  utilize  them  for  this  purpose,  how- 
ever, are  based  on  a  misunderstanding  of  the  nature  of  the  raw  mate- 
rial and  of  the  proposed  products. 

Various  Kinds  of  Sugar. — Sugar,  in  the  common  use  of  the  wrord, 
means  dry,  granulated  or  crystallized  sucrose.  This  is  only  one  of 
several  sugars  and  one  which  cannot  be  produced  from  grapes  because 
they  contain  none.  Grapes  contain  however,  two  sugars,  glucose  and 
levulose,  both  of  which  are  wholesome  foods.  The  sweetness  of  glucose 
is  less  than  that  of  sucrose,  but  that  of  levulose  is  greater.  The  mixture 
known  as  grape  sugar*  has  about  the  same  degree  of  sweetness  as 
sucrose,  usually  called  cane  sugar. 

At  present,  no  method  is  known  by  which  the  sugar  in  grapes  can 
be  given  the  dry,  granulated  texture  required  in  commercial  sugar.  A 
sugar  syrup,  however,  can  be  made  from  grapes  and  their  sweetness 
utilized  in  this  way. 

Sugar  Syrups. — Sweet  syrups  are  of  various  kinds  which  it  is  neces- 
sary to  distinguish  and  understand  before  attempting  the  manufacture 
of  any  of  them. 

A  syrup  can  be  made  by  dissolving  pure  cane  sugar  in  a  little 
water.  Such  a  syrup  is  that  used  in  canning.  It  is  perfectly  neutral 
in  flavor,  that  is,  it  has  no  taste  but  that  of  sweetness.  Similar  neutral 
syrups  can  be  made  in  the  same  way  from  pure  glucose  or  other  sugar. 

Syrups  of  varying  flavors,  on  the  other  hand,  can  be  made  from 
impure  cane  or  other  sugars.  The  syrups  commonly  sold,  such  as 
maple  syrup,  sorghum  syrup,  corn  syrup,  "golden  syrup,"  and  mo- 
lasses are  of  this  character.  The  flavors  may  be  agreeable  or  disagree- 
able, according  to  the  nature  of  the  impurities  to  which  they  are  due. 


*What  is  often  known  in  commerce  as  "  grape  sugar"  is  simply  glucose  and 
is  made  from  corn  or  other  starchy  material.  It  is  less  sweet  than  real  grape 
sugar. 


228  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 

These  impurities,  moreover,  may  be  wholesome,  unwholesome,  or 
indifferent. 

If  the  flavors  are  agreeable  and  the  impurities  harmless  the  syrup 
may  be  preferable  for  some  purposes  to  pure,  neutral  cane  sugar 
syrup.  This  is  the  case  for  some  tastes  with  maple  syrup  and 
others,  and  when  a  market  is  established  for  such  syrups,  they  com- 
mand a  higher  price  than  the  neutral  syrups  with  which  they  do  not 
compete.  On  the  other  hand,  if  the  flavors  are  not  agreeable,  the 
syrups  must  compete  with  neutral  syrups  and  this  they  can  do  success- 
fully only  by  being  sold  at  a  lower  price. 

Grape  Syrup. — To  manufacture  and  market  grape  syrup  success- 
fully, we  must  therefore  attain  one  of  the  following  results : 

1.  Produce  a  neutral  syrup  that  can  be  sold  profitably  at  the  same 
price  as  cane  sugar  syrup. 

2.  Produce  a  syrup  of  inferior  quality  that  can  be  sold  profitably 
at  a  lower  price  than  cane  sugar  syrup. 

3.  Produce  a  syrup  of  superior  quality  that  will  attract  consumers 
at  a  price  higher  than  that  of  ordinary  cane  syrup. 

Preliminary  tests  indicate  that  probably  the  first  two  results  can- 
not be  obtained  under  ordinary  conditions  of  the  market.  To  raise 
grapes  profitably  they  should  bring  at  least  $15  per  ton  and  this 
would  represent  a  cost  of  close  to  4  cents  per  pound  for  the  sugar 
they  contain.  To  this  cost  must  be  added  the  expenses  of  manufacture 
which  would  bring  the  cost  of  the  finished  syrup  higher  than  that 
ordinarily  ruling  for  cane  sugar  syrup.  With  the  present  high  cost  of 
cane  sugar,  a  neutral  grape  syrup  might  be  sold  for  a  price  that  would 
make  it  possible  to  pay  $15  or  more  per  ton  to  the  growers.  Grapes 
this  year,  however,  are  bringing  much  more  than  this  for  other  pur- 
poses, and  if  the  price  of  grapes  falls,  it  is  probable  that  that  of  sugar 
will  fall  in  proportion. 

The  only  chance  of  making  grape  syrup  profitably  as  a  permanent 
industry,  therefore,  seems  to  be  to  obtain  a  product  that  will  command 
a  price  higher  than  that  of  the  ordinary  cheap  syrups.  It  can  do  this 
only  if  it  possesses  qualities  that  are  preferred  by  consumers.  It 
must,  in  other  words,  be  sold  on  a  basis  similar  to  that  of  maple 
syrup. 

The  more  distinct  the  flavor,  providing  it  is  agreeable,  the  more 
likely  it  is  to  find  and  keep  a  permanent  profitable  market.  It  would 
seem  a  mistake,  therefore,  to  attempt  to  make  a  syrup  of  neutral  flavor 
to  compete  with  cane  syrup. 

Nature  of  the  Investigations. — The  two  problems  to  be  solved 
than  are: 


GRAPE  SYRUP  229 

(1)  Can  a  grape  syrup  be  made  that  will  be  bought  for  its  special 
qualities?  and 

(2)  Can  it  be  produced  and  sold  at  prices  which  will  attract  the 
consumer  and  pay  the  grape  grower? 

The  production  of  grape  syrup  involves:  (1)  growing  the  grapes, 
(2)  extracting  the  juice,  (3)  concentrating  the  syrup. 

No  changes  are  necessary  in  growing  the  grapes.  Cull  table  grapes, 
second-crop  raisin  grapes,  and  in  case  of  the  prohibition  of  wine- 
making,  wine  grapes  are  the  available  raw  material. 

Wineries  are  already  equipped  for  extracting  the  juice  for  wine- 
making  purposes  and  would  require  few  changes  or  additions  to  pre- 
pare juice  for  syrup  making. 

Condensers  for  making  the  grape  syrup  needed  in  sweet  wine 
already  exist  in  many  wineries.  Their  output,  however,  is  small  and 
the  product  not  well  suited  for  the  object  in  view.  They  would  have 
to  be  considerably  modified  and  expanded  to  be  of  much  use  in  mak- 
ing table  syrup.  The  beet-sugar  factories,  however,  have  a  very  large 
capacity,  sufficient  to  handle  all  the  grapes  grown  in  California  and 
could  be  adapted  to  the  manufacture  of  grape  syrup  with  little 
change.  As  they  are  idle  for  several  months  in  the  year,  they  could 
easily  concentrate  all  the  grape  juice  that  would  be  available  if  this 
juice  could  be  obtained  during  the  proper  season  of  the  year.  This 
season  is  the  spring  and  summer  when  they  are  not  busy  with  beets. 

One  of  the  main  problems,  therefore,  is  the  keeping  and  storage  of 
the  juice  from  the  vintage  to  the  spring. 


IT.  GKAPE  JUICE 

Amount  of  Sugar  in  the  Grapes. — The  riper  the  grapes  the  more 
sugar  they  contain  and  the  more  syrup  they  will  yield.  Cull  table 
grapes  at  the  beginning  of  the  season  may  show  a  sugar  content  as 
low  as  15%  (Balling  degrees),  towards  the  end,  as  high  as  25%. 
Wine  grapes  are  usually  gathered  when  they  show  22%  to  23%,  but 
may  be  gathered  as  low  as  19%  or  as  high  as  27%. 

One  hundred  gallons  of  juice  at  23°  Balling  contains  close  to 
190  pounds  of  grape  sugar;  at  19°  Balling,  only  about  157  pounds; 
but  at  27°  Balling,  about  223  pounds. 

Separating  the  Juice. — The  volume  of  one  ton  of  stemmed  grapes 
at  23°  Balling  is  29  cubic  feet  or  219  gallons.  This  consists  of 
skins,  seeds,  and  juice  in  varying  proportions.  The  average  volume 
of  juice  actually  present  may  be  taken  as  about  190  gallons,  but  it 
will  vary  from  175  to  210,  according  to  the  variety  and  the  develop- 


230  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 

ment  of  the  berry.  There  is  a  little  more  than  this  in  grapes  below, 
and  a  little  less  in  grapes  above  23°  Balling.  The  difference  is  about 
1  gallon  per  ton  for  each  degree  Balling. 

Wineries,  by  crushing  and  pressing  the  grapes,  can  separate  more 
or  less  of  this  juice  from  the  solid  parts  of  the  grapes.  The  average 
volume  of  juice  extracted  in  this  way  from  unfermented  grapes  will 
not  much  exceed  150  gallons  per  ton.  The  remainder,  about  one- 
fifth  of  the  whole,  is  retained  by  the  pomace  (solid  matter).  By 
repressing  or  by  using  more  powerful  presses  a  little  more  juice  can 
be  obtained  but  the  cost  is  high.  By  leaching  with  hot  water  nearly 
all  the  juice  can  be  obtained  but  in  a  more  or  less  diluted  form. 

Extracting  the  Pomace. — The  juice  remaining  in  the  pomace  can 
be  separated  by  the  use  of  water  in  several  ways.  For  example :  ( 1 ) 
by  sprinkling  hot  water  on  top  of  the  pomace  in  a  tall  vat  open  below. 
The  water  dripping  through  the  pomace  will  leach  out  a  large  part 
of  the  remaining  sugar;  (2)  by  allowing  hot  water  to  stand  on  the 
pomace  in  a  vat  for  several  hours  and  then  drawing  off  the  liquid 
and  pressing  the  pomace  again;  (3)  by  connecting  together  a  bat- 
tery of  several  vats  filled  with  pomace  and  passing  a  stream  of  water 
downwards  through  the  series.  The  juice  is  extracted  in  this  method 
by  diffusion  and  displacement. 

In  all  these  methods  the  water  must  be  very  hot  to  destroy  the 
power  of  the  pulp  cells  to  retain  the  juice.  The  first  method  is  the 
simplest  but  the  extraction  is  imperfect ;  the  second  requires  repress- 
ing and  is  laborious ;  the  third  is  the  most  efficient,  but  requires 
expensive  equipment. 

A  laboratory  test  of  the  second  method  with  90  pounds  of  grapes 
gave  the  following  results : 

YIELD  PER  TON  OF  GRAPES 

First    pressing    136.00  gals,  at  18°      Balling- 
Second  pressing  (after  application  of  hot  water)    153.75  gals,  at    7?2    Balling 

Total  289.75  gals,  at  12?27  Balling 

Volume  of  1  ton  grapes  at  18°   Balling  223.5  gallons 

Volume    of    juice    present    (calculated    from    weight    of 

dry    pomace)     214.4  gallons 

Volume  of  recovered  juice  (reduced  to  18°  Balling)  197.5  gallons 

Juice  recovered,  per  cent  of  volume  of  grapes  88.4  per  cent 

Juice  recovered,  per  cent  of  juice  present   92.1  per  cent 

Pomace  recovered,  per  cent  of  volume  of  grapes  11.6  per  cent 

Sugar  in  juice  recovered   (calculated)   291     pounds 


GRAPE  SYRUP  231 

Another  test  made  with  35.2  pounds  of  Sultanina  grapes  of  23 ?1 
Balling,  gave  the  following  results: 

YIELD  PEE  TON  OF  GEAPES  ,,  ,    , 

Per  cent  oi 

volume  of 

grapes 

First  pressing,  137  gallons  at  23?1  62.7 

Second  pressing,  51.3  gallons  (reduced  to  23?1)   23.4 

Third  pressing,  16.4  gallons   (reduced  to  23?1)   7.5 

Total:     204.7   gallons    (reduced  to  23?  1)    93.6 

Sugar  in  juice  recovered   (calculated)   391    pounds 

Preservation  of  the  Juice. — Grapes,  even  if  carefully  gathered 
and  handled,  will  keep  in  good  condition  at  most  for  only  a  few  days. 
The  juice,  however  carefully  handled,  will  commence  to  ferment  in 
a  few  hours  after  extraction.  Most  vineyards  are  so  situated  that 
the  grapes  can  be  brought  in  good  condition  to  the  winery,  but  once 
there  they  must  be  crushed  quickly  or  they  will  spoil.  As  soon  as  the 
juice  is  extracted  it  must  be  made  into  syrup  or  preserved  in  some  way. 

As  the  vintage  in  any  one  locality  lasts  only  four  or  five  weeks, 
it  would  be  impracticable  to  make  the  syrup  as  fast  as  the  grapes  were 
harvested.  Some  means  of  preserving  the  juice  for  several  months, 
preferably  8  or  10,  is  therefore  needed. 

The  only  method  at  present  known  that  seems  practicable  is  the 
use  of  sulfurous  acid  (SO.,). 

Amount  of  Sulfurous  acid  Needed. — Preliminary  experiments 
demonstrated  that  liquefied  sulfurous  acid  or  a  water  solution  of 
sulfurous  acid  were  the  forms  most  suited  for  this  purpose.  Fumes 
of  burning  sulfur  are  hard  to  control  and  sulfites  leave  too  much 
potash  or  other  base  in  the  product.  Sulfurous  acid  can  be  com- 
pletely removed. 

Tests  were  made  on  small  laboratory  samples  (500  c.c.)  of  juice 
and  on  larger  lots  in  25  and  50  gallon  barrels.  Sulfurous  acid  was 
added  in  amounts  varying  from  300  to  2000  milligrams  per  liter.  This 
corresponds  to  .03%  to  0.2%. 

All  samples  with  1000  milligrams  or  less  fermented  within  a  fewr 
weeks.  The  sample  with  1250  milligrams  kept  perfectly  for  two 
months,  when  it  was  used.  Fifty  gallons  in  a  barrel  treated  with 
2000  milligrams  kept  from  September  until  July  of  the  following 
year.  The  large  lots  were  stored  in  a  shed  where  the  temperature 
varied  greatly  and  was  often  very  hot.  It  seems  probable,  therefore, 
that  1500  milligrams  of  sulfurous  acid  per  liter  would  be  sufficient 
to  preserve  grape  juice  for  ten  months  under  any  ordinary  condi- 


232  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 

tions.  This  corresponds  to  1.25  pounds  of  liquid  sulfurous  acid  or 
2.5  gallons  of  6  per  cent  sulfurous  acid  solution  to  100  gallons  of  juice 
(=0.15%  S02). 

It  has  been  found  that  the  riper  the  grapes,  the  more  sulfurous 
acid  is  necessary  for  preservation.  The  presence  of  moldy  or  other 
spoiled  grapes  has  a  similar  effect. 

Storage  of  Treated  Juice. — Juice  containing  sulfurous  acid  should 
not  remain  in  contact  with  any  metal.  It  can  be  stored  in  barrels  or 
other  wooden  vessels.  These  should  be  sterilized  with  steam  and  kept 
sulfur ed  while  empty.  When  containing  juice,  they  should  be  com- 
pletely filled  and  not  bunged  too  tight.  If  only  partially  filled, 
sulfurous  acid  will  be  lost  by  evaporation  from  the  surface  and  if  the 
bungs  are  driven  too  tight,  the  barrels  may  explode  if  fermentation 
starts. 

The  filled  barrels  should  be  watched  closely  and  on  the  first  signs 
of  fermentation  treated  with  a  new  dose  of  sulfurous  acid,  about 
1000  milligrams  per  liter ;  that  is,  1%  gallons  6  per  cent  sulfurous 
acid  solution  per  100  gallons. 

If  the  filled  barrels  are  to  be  stored  for  some  time  they  should  be 
placed  so  that  the  clear  juice  can  be  drawn  off  after  the  sediment 
settles.  They  should  be  wedged  firmly  to  prevent  movements  of  the 
liquid  and  kept  in  as  even  and  cool  a  temperature  as  is  available. 

Transporting  the  Juice. — After  storing,  a  more  or  less  bulky  sedi- 
ment will  be  formed,  equal  to  about  5%  of  the  total  volume  of  the 
juice.  For  shipping,  the  clear  juice  should  be  carefully  drawn  off 
the  sediment  into  clean  sterilized  barrels.  The  racking  should  be 
done  with  as  little  disturbance  of  the  liquid  as  possible  and  as  little 
exposure  to  the  air.  Care  in  storing  and  racking  facilitates  clearing 
at  the  syrup  factory. 


III.  MANUFACTURE  OF  THE  SYRUP 

Clearing  the  Juice. — Sulfited  juice  after  standing  and  careful 
racking  is  usually  clear.  If  not  clear  when  it  arrives  at  the  factory 
it  must  be  filtered  or  fined  (clarified)  before  concentration. 

If  the  juice  is  only  moderately  cloudy,  it  can  be  clarified  with 
casein ;  if  very  cloudy,  a  mixture  of  casein  and  Spanish  Clay  is  better. 
Both  methods  were  used  successfully  in  our  experiments. 

Commercial  casein  free  from  bad  odors  and  T.  P.  (technically 
pure)  ammonia  were  mixed  in  the  proportion  of  1  pound  of  the  former 
to  14  pint  of  the  latter.  These  were  placed  with  1  quart  of  water  in  a 
kettle  and  allowed  to  stand  about  an  hour  to  soften  the  casein.    Two 


GRAPE  SYRUP  233 

gallons  of  water  was  then  added  and  boiled  and  stirred  until  there 
was  practically  no  smell  of  ammonia  and  then  enough  water  added 
to  bring  the  total  volume  to  4  gallons.  This  gives  a  3% -solution  of 
casein,  of  which  three  gallons  is  sufficient  for  100  gallons  of  juice. 

Spanish  Clay  whs  mixed  with  water  at  the  rate  of  one  pound  to 
one  gallon  of  water.  The  mixing  must  be  continued  until  a  thin 
homogeneous  mud  is  formed,  free  from  lumps.  A  convenient  method 
is  to  place  the  clay  and  water  in  a  small  barrel  which  is  rotated  length- 
wise by  means  of  a  pulle}^  on  a  shaft  passed  through  it  short  diameter. 
From  5  to  10  gallons  of  this  clay  mixture  is  used  for  100  gallons  of 
juice. 

The  clarifjdng  liquids  are  added  slowly  to  the  juice  with  constant 
stirring  or  pumping  over.  The  juice  is  then  boiled,  allowed  to  stand 
from  12  to  18  hours,  and  the  clear  juice  drawn  off.  The  sediment  can 
be  filtered. 

Clarifying  is  most  conveniently  done  in  connection  with  the  re- 
moval of  the  sulfurous  acid,  as  described  in  the  next  paragraph. 
After  adding  the  clarifying  material,  the  desulfiting  current  of  steam 
is  passed  through  the  juice.  The  casein,  besides  clearing,  helps  to 
decolorize  the  juice. 

Removal  of  the  Sulfurous  Acid. — The  finished  syrup  must  contain 
practically  no  sulfurous  acid.  That  contained  in  the  juice  therefore 
must  be  removed  during  the  process  of  manufacture. 

Many  methods  were  tested  for  this  purpose,  but  all  failed  more  or 
less  except  one.  Boiling  down  the  juice  to  a  syrup  removed  an  amount 
about  in  the  ratio  of  the  concentration;  that  is,  the  syrup  contained 
about  the  same  per  cent  of  sulfurous  acid  as  the  juice  from  which  it 
was  made.  Passing  streams  of  various  gases  through  the  juice  also 
gave  imperfect  results.  A  stream  of  compressed  air  passed  through  the 
juice  which  was  kept  at  140  to  180°  F.  removed  the  sulfurous  acid 
with  fair  rapidity  but  not  completely. 

A  thoroughly  satisfactory  method  was  found  in  passing  a  current 
of  steam  through  the  boiling  juice.  The  steam  was  conducted  into  the 
cold  juice  held  by  a  wooden  container  until  the  juice  reached  the  boil- 
ing point.  The  steam  was  then  passed  rapidly  through  the  boiling 
juice  until  all  the  sulfurous  acid  was  removed,  which  required  from 
30  to  35  minutes  in  the  5-gallon  lots  used.  All  contact  with  metals 
should  be  avoided  in  this  process. 

Decolorization, — If  a  light-colored  syrup  is  to  be  produced,  the 
juice  of  red  grapes  and  probably  also  of  white  grapes  will  have  to  be 
decolorized.  Of  the  methods  tested,  treatment  with  bone  black, 
gave  the  best  results.    Bone  black  free  from  objectionable  odors  and 


234  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 

flavors  and  containing  little  or  no  metallic  oxides  or  carbonates  should 
be  chosen  and  preferably  washed  with  acid  before  use. 

In  our  small-scale  tests,  powdered  bone  black  was  found  best.  In 
commercial  work,  probably  the  coarse  bone  black  used  in  the  usual 
decolorizing  "towers"'  of  sugar  factories  would  be  better. 

In  the  manufacture  of  cane  sugar,  the  juice  is  concentrated  to 
from  45°  to  60°  Brix  before  decolorization,  to  reduce  the  volume  to 
be  handled.  A  similar  practice  would  be  convenient  with  grape 
juice. 

The  bone  black  in  time  will  lose  its  decolorizing  power,  but  may  be 
"revivified"  by  mixing  with  a  small  amount  of  sodium  carbonate 
(soda  ash)  and  heating  in  a  closed  retort  to  carbonize  the  organic 
matter  absorbed  by  the  bone  black.  The  bone  black  is  then  leached 
with  water  to  remove  the  sodium  salts.  An  amber  colored  syrup  can 
be  produced  from  light  colored  juice  without  the  use  of  bone  black. 

Deacidification. — Juice  from  ripe  grapes  contains,  on  the  average, 
about  0.7%  of  acid  expressed  as  tartaric  acid.  This  is  mostly  cream 
of  tartar  (KHC4H406)  and  some  tartaric  acid  (H2C4H406).  If  the 
acidity  is  not  reduced  it  will  cause  the  syrup  to  be  too  sour  for  most 
tastes.  The  best  material  found  for  reducing  the  acidity  was  calcium 
carbonate.  An  excess  does  no  harm  as  both  the  calcium  carbonate 
added  and  the  calcium  tartrate  formed  are  insoluble  and  can  be 
removed.  A  part  of  the  calcium  salts  does  not  precipitate  immediately 
but  gradually  forms  a  cloudiness  in  the  syrup  on  standing  but  can 
be  then  removed  by  decantation  or  filtration.  Sodium  carbonate 
(Na2C03)  or  caustic  potash  (KOH)  leave  soluble  salts  in  the  syrup, 
and  lime  (CaO)  in  excess  spoils  it. 

Decolorization  is  more  rapid  and  requires  less  bone  black  while 
the  juice  is  acid.  It  should  therefore  precede  deacidification.  If  it 
follows  deacidification,  the  alkaline  salts  in  the  bone  black  will  make 
the  juice  alkaline  and  this  cannot  then  be  decolorized. 

Concentration  of  the  Juice. — In  reducing  the  juice  to  a  syrup,  the 
object  is  to  obtain  a  product  of  the  desired  concentration  with  as  little 
change  in  flavor  and  color  as  possible. 

If  we  evaporate  the  juice  by  heating  in  an  open  vessel,  a  compara- 
tively high  temperature  is  necessary  which  results  in  destroying  much 
of  the  grape  flavor  and  in  giving  a  cooked  taste  and  dark  color. 

In  the  Waterhouse  process,  high  temperatures  are  eliminated.  The 
process  consists  essentially  of  evaporating  the  juice  on  strips  of  cloth 
exposed  to  the  sun  and  dry  air.  The  resulting  syrup  is  dark  colored 
and  has  a  raisin  or  cooked  taste.  This  indicates  that  the  action  of  the 
oxygen  of  the  air  is  as  harmful  as  that  of  high  temperatures. 


GRAPE  SYRUP  235 

The  usual  method  of  making  syrup  on  an  industrial  scale  is  by 
means  of  evaporation  in  a  partial  vacuum.  This  method  makes  it 
possible  to  concentrate  the  juice  at  a  lower  temperature  than  boiling 
in  an  open  vessel  and  removes  most  of  the  air  in  contact  with  the 
juice  during  the  process. 

The  vacuum  pans  used  in  this  method  are  of  various  types,  some 
of  "quintuple"  or  "triple  effect,"  and  continuous  operation,  in  which 
the  process  is  rapid  and  consequently  the  time  of  exposure  of  the 
juice  to  heat  short.  In  other  types  the  evaporation  is  discontinuous 
and  the  concentration  takes  place  in  a  single  vacuum  pan.  The  time 
of  exposure  to  heat  in  the  latter  types  is  much  longer. 

A  small  vacuum  pan  of  the  latter  type  was  used  in  the  experi- 
ments. It  was  operated  with  a  vacuum  of  24  inches  and  steam  of  30 
pounds'  pressure.  Under  these  conditions,  concentration  required 
about  2!/2  hours.  The  higher  the  vacuum  and  the  more  rapid  the 
evaporation,  especially  during  the  last  stages  of  concentration  the 
lighter  colored  and  better  flavored  the  syrup.  It  seems  probable, 
therefore,  that  regular  triple  or  quintuple  vacuum  pans  of  sugar 
factories  would  yield  a  syrup  of  better  quality  than  that  obtained 
in  our  experiments. 

The  care  taken  to  avoid  prolonged  contact  of  the  sulfited  juice 
with  metal  is  not  necessary  during  concentration  because  the  sulfurous 
acid  has  been  eliminated  and  all  other  acids  much  reduced. 

All  these  processes  of  concentration  are  based  on  the  fact  that 
sugar  syrup  has  a  higher  boiling  point  than  that  of  pure  water. 
Therefore,  when  we  raise  the  temperature  of  the  juice  to  the  boiling 
point  of  water  (whether  at  air  pressure  or  in  a  partial  vacuum),  the 
water  evaporates  from  the  juice  and  leaves  the  syrup. 

Other  processes  are  based  on  the  fact  that  sugar  syrup  has  a  lower 
freezing  point  than  water.  Therefore,  when  we  lower  the  temperature 
of  the  juice  to  the  freezing  point  of  water  or  a  little  lower,  the  water 
is  precipitated  or  separated  as  a  solid  (ice)  and  can  be  removed,  leav- 
ing the  syrup.  These  processes  offer  the  most  promising  means  of 
obtaining  a  syrup  retaining  the  high  flavor,  light  color,  and  other 
qualities  of  the  juice  as  little  changed  as  possible.  They  are  not  used 
commercially  in  California  and  were  not  tested  in  the  present  investi- 
gation. 

Degree  of  Concentration. — If  the  syrup  is  concentrated  to  above 
65°  Balling,  part  of  the  glucose  will  crystallize  on  standing.  If  the 
syrup  is  much  below  65°  Balling,  it  will  appear  thin.  The  finished 
syrup  therefore  should  be  as  near  this  point  as  possible.  Syrup  of  this 
concentration  will  show  62°  as  it  comes  hot  from  the  evaporating  pan. 


236  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 

Settling  the  Syrup. — As  the  syrup  comes  from  the  pan,  it  contains 
an  excess  of  calcium  tartrate.  This  is  solid  and  will  settle  out  in 
about  two  weeks  if  the  syrup  is  left  in  large  vats.  The  clear  syrup 
can  then  be  drawn  off  and  placed  in  containers  for  sale.  The  syrup 
in  the  lees  can  be  recovered  by  means  of  a  filter  press.  The  "cake" 
from  the  press  can  then  be  washed,  the  washings  concentrated  to 
syrup,  and  the  solid  matter  dried  and  sold  to  cream  of  tartar  factories. 

Packing. — The  finished  syrup  can  now  be  placed  in  the  final  con- 
tainers. These  may  be  cans,  bottles,  or  barrels.  Cans  are  perhaps 
to  be  preferred  as  they  are  most  convenient.  The  syrup  has  no  effect 
on  the  metal. 

Sterilizing. — The  syrup  does  not  spoil  easily,  but  in  time  may 
mold  or  ferment  unless  sterilized.  If  packed  in  barrels,  these  should 
be  sterilized  and  the  juice  run  in  at  a  temperature  between  140°  P 
and  160°  F.  If  placed  in  cans  or  bottles  these  should  be  sterilized  25 
minutes  for  quarts,  to  35  minutes  for  gallons,  at  155°  F  to  160 °F. 
Longer  heating  or  higher  temperatures  darken  the  syrup.  The 
sterilization  is  carried  out  exactly  as  with  fruit. 

IV.  OUTLINE  OF  METHOD 

(Based  on  Experimental  Work) 

1.  Use  ripe  grapes,  preferably  25°  Balling  or  higher. 

2.  Crush  and  press  as  soon  after  picking  as  possible.  Use  ordi- 
nary winery  equipment. 

3.  Extract  the  juice  from  the  pomace  by  progressive  washing 
with  boiling  water  and  steam,  and  two  supplementary  pressings.  Mix 
the  liquid  from  the  first  extraction  with  the  undiluted  juice  and  use 
the  liquid  from  the  last  extraction  for  the  first  extraction  of  the  next 
lot  of  pomace. 

4.  Add  1500  milligrams  of  sulfurous  acid  per  liter  to  the  juice 
and  store  in  clean,  completely  filled  and  lightly  bunged  wooden  tanks. 

5.  Rack  from  the  sediment,  avoiding  contact  with  air  and  ship  in 
wood  to  the  sugar  factory. 

#6.  Desulfite  with  steam  (and  clarify  at  the  same  time  if  neces- 
sary). 

7.  Decolorize  with  bone  black  if  a  very  light  colored  juice  is 
desired. 


*  It  might  be  preferable  in  practice  to  desulfite  the  juice  at  the  winery  before 
shipping  to  the  syrup  factory.  This  could  be  done  in  open  wooden  vats  with 
pressure  steam.  This  would  cause  a  partial  concentration  and  reduction  of 
about  50  per  cent  in  volume  which  would  decrease  transportation  charges.  The 
removal  of  the  sulfurous  acid  would  also  make  it  possible  to  ship  the  juice 
in   metal  containers. 


GRAPE  SYRUP  237 

8.  Filter. 

9.  Deacidify  with  calcium  carbonate. 

10.  Filter. 

11.  Concentrate  to  65°  Balling  in  triple-effect  vacuum  pans. 

12.  Allow  to  settle  2  weeks  in  clean  tanks. 

13.  Pack  in  gallon,  quart,  or  pint  cans. 

14.  Pasteurize  25  to  35  minutes. 

15.  Cool  in  water. 


V.  SPECIAL  SYRUPS 

The  experiments  detailed  above  and  the  method  suggested  had  for 
their  object  the  production  of  a  syrup  as  much  like  the  syrups  in 
common  use  as  possible.  These  syrups  are  all  neutral  in  flavor,  low 
in  acid,  and  light  in  color. 

By  omitting  or  moderating  the  deacidification,  a  syrup  can  be 
made  with  any  desired  amount  of  acidity. 

By  using  certain  processes  which  retain  more  or  less  the  flavors  of 
the  grape,  syrups  of  various  high  and  agreeable  flavors  can  be  pro- 
duced. 

By  using  red  grapes  and  omitting  the  decolorization,  red  and  pink 
syrups  of  attractive  color  can  be  obtained. 

By  evaporating  in  open  kettles  after  deacidification  a  dark  syrup 
with  a  pleasing  molasses  flavor  and  suitable  for  table  use  is  obtained. 

These  special  syrups  could  be  used  in  the  preparation  of  sweet 
beverages,  in  ice  creams,  jams,  and  in  cooking,  and  would  undoubtedly 
be  found  useful  and  excellent  by  many. 

VI.  MARKETING  THE  SYRUP 

The  successful  marketing  of  the  syrup  depends  on  finding  con- 
sumers who  are  attracted  by  its  quality  and  price. 

To  test  the  possibilities  in  this  respect  a  quantity  of  syrup  was 
placed  on  sale  through  the  co-operation  of  a  local  grocer.  It  was  put 
up  in  pint  bottles  and  tins  holding  13%  ounces.  These  were  sold  for 
20  cents  a  tin  and  25  cents  a  bottle,  a  price  somewhat  higher  than  that 
of  ordinary  cane  or  corn  syrup  at  the  time,  but  lower  than  that  of 
good  maple  syrup. 

Purchasers  were  asked  to  give  their  opinion  on  its  quality,  and 
the  results  were  encouraging.  Of  sixty-five  opinions  given,  43  were 
favorable,  18  more  or  less  unfavorable,  and  4  non-committal.  The 
following  is  a  summary  of  these  opinions : 


238  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 


SUMMARY   OF   OPINIONS 

Very  good,  lovely,  excellent,  very  nice 23 

Good — no  unfavorable  comment 20 

Disliked  it — no  specific  criticism  5 

Too   sweet 2 

Not  sweet  enough,  too  thin 6 

Tastes   cooked,   burned,   strong 6 

Doubtful 4 


Less  than  8%  of  those  reporting  found  it  without  merit.  About 
25%  liked  it,  but  found  various  defects.  The  remaining  66%  found 
nothing  to  criticise  and  of  these  more  than  half  praised  it  highly. 

These  reports  are  more  favorable  than  could  have  been  anticipated 
when  we  consider  that  grape  syrup  differs  very  considerably  in  flavor 
from  all  the  syrups  with  which  most  people  are  familiar.  A  marked 
difference  in  the  taste  of  a  common  article  of  food  will  nearly  always 
give  an  unfavorable  impression  even  if  it  is  an  agreeable  difference. 

The  commonest  criticism  was  that  the  syrup  tasted  cooked  or 
burned.  This  taste,  which  a  few  liked,  is  due  in  part  to  the  long  heat- 
ing necessary  with  the  type  of  evaporator  used.  With  the  the  con- 
tinuous evaporators  used  in  sugar  factories  it  would  be  diminished 
or  even  eliminated. 

The  only  other  criticism  that  was  made  several  times  was  that  the 
syrup  was  too  thin  or  not  sweet  enough.  It  is  not  quite  so  heavy  as 
ordinary  cane  syrup  and  its  slight  acidity  makes  it  taste  less  sweet. 
This  it  would  be  difficult  to  overcome.  If  all  the  acidity  were  removed, 
the  color  would  be  darkened  and  the  cooked  taste  intensified.  If  it 
were  made  heavier  it  would  be  liable  to  solidify  in  the  can.  However, 
less  than  10  per  cent  of  the  tasters  found  that  these  characteristics 
were  defects  and  these  characteristics,  together  with  the  special 
flavor  of  grapes,  would  be  some  of  the  qualities  which  would  attract 
the  special  consumers  upon  which  the  syrup  must  depend  for  its 
market. 

More  detailed  reports  were  received  from  a  number  of  consumers. 
Some  found  the  syrup  very  agreeable  for  table  use  when  used  on  rice 
and  mush,  boiled  or  fried,  or  with  hot  cakes,  corn  bread,  and  biscuits. 

Several  tested  the  grape  syrup  in  cooking  and  found  it  excellent 
in  making  cakes,  cookies,  corn  bread,  ginger  bread,  puddings,  and 
pies.  Cakes  and  cookies  made  with  grape  syrup  remained  moist  longer 
than  when  made  with  ordinary  sugar. 

Excellent  jams  and  fruit  butters  were  made  from  dark  colored 
fruits.    Good  results  were  obtained  when  grape  syrup  was  substituted 


GRAPE  SYRUP  23!) 

for  sugar  at  the  rate  of  one  cup  of  syrup  for  one  of  sugar.  In  jams 
made  from  light  colored  fruits  the  results  were  less  satisfactory. 

Attempts  to  use  grape  syrup  in  the  preparation  of  jellies  and 
marmalades  were  not  successful. 

Tests  of  the  use  of  grape  syrup  in  canning  were  encouraging. 
Certain  fruits,  such  as  loganberries,  black  cherries,  and  some  peaches 
were  as  good  when  canned  with  grape  syrup  as  with  sugar.  Apricots 
were  improved  in  color,  but  the  flavor  was  less  fresh.  Pears  were 
darkened  somewhat  but  the  flavor  was  good.  In  these  tests,  cans  in 
which  only  grape  syrup  was  used  were  compared  with  cans  in  which 
only  ordinary  sugar  was  used.  They  indicate  that  a  mixture  of  sugar 
and  grape  syrup  in  the  ratio  of  25%  to  50%  of  the  latter  would  give 
good  results  in  nearly  all  cases. 

VII.  YIELDS  AND  COSTS 

We  can  make  an  estimate  of  the  amount  of  syrup  that  a  ton  of  grapes 
should  yield  by  using  the  following  formula: 

b  X  s 

G  — X  g 

B  X  S 

where 

G  =  Gallons  of  syrup. 
~b  =  Balling  degree  of  juice. 
s  =  Specific  gravity  of  juice. 
B  =  Balling  degree  of  syrup. 
S  —  Specific  gravity  of  syrup. 
g  s=  Gallons  of  juice  obtained  from  1  ton  of  grapes. 

If  we  assume  200  gallons  as  the  average  amount  of  juice  obtain- 
able by  the  methods  described,  this  formula  would  give  us  for  grapes 
of  various  degrees  of  ripeness  the  amounts  of  syrup  of  65°  Balling 
shown  below. 

YIELD  OF  SYRUP  (65°  BAL.)  FROM  ONE  TON  OF  GRAPES  AT  VARIOUS 

DEGREES  BALLING 

(Calculated)  Gallons  of  65°  syrup 

By  2  V2  times 
Balling  of  juice  By  formula  Balling 

Juice  of  18°   Balling  45.0  45.0 

Juice  of   19°    Balling  47.7  47.5 

Juice  of   20°    Balling   50.4  50.0 

Juice  of  21°    Balling   53.2  52.5 

Juice  of  22°    Balling   56.0  55.0 

Juice  of  23°    Balling 58.7  57.5 

Juice  of  24°   Balling 61.5  60.0 

Juice  of   25°    Balling   64.2  62.5 


240  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 

This  indicates  that  if  practically  all  the  juice  were  extracted  a 
ton  of  grapes  would  yield  a  number  of  gallons  of  65°  Balling  syrup 
equal  to  2%  times  the  Balling  degree  of  the  juice.  The  formula 
gives  a  higher  figure  for  the  sweeter  grapes  but  as  these  grapes  yield 
a  smaller  volume  of  juice  a  calculation  made  by  multiplying  the 
Balling  degree  by  2%  would  be  nearer  the  actual  facts. 

Experimental  data  corroborate  these  theoretical  calculations. 


YIELD  OF  SYEUP  (65°  BAL.)  FEOM  ONE  TON  OF  GEAPES 

(From  Experimental  Data) 

Per  cent  of 
Gallons  of  volume  of       Balling  per  cent  Gallons  of  syrup 

Experiment  juice  grapes  of  juice  Found  Calculated 

1  197.5  88.4  18.0  44.4  45.0 

2  204.7  93.6  23.1  59.1  57.8 

In  Experiment  1  the  volume  of  syrup  is  a  little  less  than  the  cal- 
culated amount  owing  to  incomplete  extraction  of  the  juice.  In 
Experiment  2  the  extraction  was  more  nearly  complete  and  the  grapes 
seedless.  Both  these  factors  increase  the  volume  of  juice  recovered 
and  the  volume  of  syrup  is  correspondingly  a  little  higher  than  the 
calculated  amount. 

At  the  price  of  20  cents  for  a  13%-ounce  tin  at  which  the  syrup  was 
retailed,  a  gallon  would  be  worth,  as  bought  by  the  consumer,  $1.98, 
or,  in  round  numbers,  $2.  A  ton  of  grapes,  therefore,  would  yield 
syrup  of  a  final  value  of  from  $90  for  grapes  of  .18°  Balling  to  $135 
for  grapes  of  25°  Balling. 

Whether  this  value  is  sufficient  to  yield  a  profit  to  the  grower  of 
the  grapes,  .the  manufacturer  of  the  juice  and  syrup,  and  the  retailer, 
is  difficult  to  calculate  from  laboratory  experiments.  We  can  make 
an  estimate,  however,  by  basing  our  calculations  on  what  is  known 
regarding  the  cost  of  growing  grapes,  of  extracting  the  juice  at  the 
wineries  for  wine  making,  of  making  syrup  in  the  sugar  factories,  and 
of  canning,  together  with  experimental  data  on  the  special  processes 
needed  in  the  manufacture  of  grape  syrup. 


GRAPE  SYRUP  241 

ESTIMATE  OF  COST  OF  PRODUCING  GRAPE  SYRUP 

Cost  per  gallon 
of  syrup 
Grapes  of  22°  Balling  at  $17.50  per  ton  $0,318 

$0,318 
Cost  of  operations  at  winery: 

Crushing,  pressing,  and  storing  at  lc  per  gal.  of  juice 036 

Treatment  with  S02  at  1500  milligrams  per  liter  027 

Transportation  to  sugar  factory  at  20c  per  100  pounds 073 

.136 
Cost  of  operations  at  sugar  factory: 

Desulfiting  at  %c  per  gal.  of  juice  020 

Decolorizing  at  %c  per  gal.  of  juice  020 

Two  filtrations  at  lc  per  gal.  of  juice  040 

Evaporation   005 

Handling  and  pumping  juice  and  syrup  010 

.095 

Cost  of  canning — cans,  boxes,  pasteurization,  labeling  .300 

Commission  of  retailer,  at  25%  .500 

Total    $1,349 

This  table  is  an  estimate  of  the  actual  cost  of  the  manufacturing 
operations,  which,  subtracted  from  the  retail  price  of  $2  per  gallon, 
leaves  a  balance  of  65  cents  per  gallon.  From  this  balance,  is  to  be 
deducted  all  fixed  charges  such  as  interest  on  investment,  depreciation 
of  equipment,  taxes,  and  insurance. 


VIII.   RAW   MATERIAL 

Under  normal  conditions  of  the  past,  there  has  been  little  grape 
material  that  could  have  been  used  for  syrup.  Under  war  prohibi- 
tion of  wine-making,  there  will  be  a  large  amount.  In  round  numbers, 
about  500,000  tons  of  grapes  have  been  absorbed  by  the  wineries 
annually.  The  average  price  paid  for  these  grapes  has  varied  from 
something  over  $22  to  about  $15  per  ton,  according  to  locality  and 
variety.  If  we  assume  an  average  price  of  $17.50,  which  is  low,  the 
grapes  taken  by  the  wineries  represent  a  value  to  the  growers  of  nearly 
$9,000,000  a  year. 

Approximately  half  of  these  grapes  are  produced  in  the  raisin 
districts.  These  could  be  dried  by  methods  well  understood  by  the 
growers  and  would,  under  present  conditions,  probably  find  a  market 
without  much  trouble,  as  inferior  raisins  for  domestic  consumption  or 
for  export  for  various  purposes. 

For  the  other  half,  or  250,000  tons,  there  is  at  present  no  pros- 
pect of  any  profitable  use  but  the  manufacture  of  syrup.    If  the  whole 


242  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 

of  this  250,000  tons  of  grapes  were  crushed  and  extracted,  50,000,000 
gallons  of  juice  would  be  obtained.  This  is  about  the  total  crushing 
and  storage  capacity  of  all  the  wineries  in  the  state.  To  preserve  all 
this  juice  there  would  be  required  400  tons  of  liquid  sulfurous  acid. 

The  concentration  of  this  juice  would  yield  about  12,000,000  gal- 
lons of  65°  Balling  syrup,  equivalent  to  about  40,000  tons  of  sugar. 
This  amount  could  easily  be  handled  by  a  few  of  the  beet-sugar  fac- 
tories of  the  state  during  the  months  they  are  usually  idle.  The 
storage  and  shipment  of  this  syrup  would  offer  difficulties,  but  these 
might  be  solved  by  the  use  of  the  large  number  of  oak  casks  made 
available  by  the  closing  of  the  distilleries. 

The  marketing  of  this  syrup  could  be  accomplished  by  govern- 
mental regulations  which  would  encourage  or  enforce  the  use  of  grape 
syrup.  Its  use  could  be  encouraged  by  a  limitation  on  individual 
purchases  of  sugar  and  cane  syrup  and  freedom  of  purchase  of  grape 
syrup.  Its  use  could  be  enforced  by  obliging  every  fruit  cannery  to 
purchase  a  certain  amount  of  grape  syrup  in  connection  with  their 
purchases  of .  sugar.  These  regulations  could  be  enforced  without 
hardship  to  manufacturer  or  consumer  and  would  result  not  only  in 
saving  the  grape  grower  from  ruin  but  in  saving  a  large  amount  of 
food  which  would  otherwise  be  lost. 


SUMMARY  AND  CONCLUSIONS 

About  250,000  tons  of  wine  and  table  grapes  cannot  be  used  next 
year   in   the   usual   way. 

This  represents  a  value  of  the  raw  material  of  over  $4,000,000, 
and  of  about  twice  this  amount  in  the  manufactured  state  as  wine,  etc. 

Their  loss  would  involve  the  ruin  of  thousands  of  grape  growers. 

If  they  were  made  into  grape  syrup  the  product  saved  would  be 
equivalent  to  over  40,000  tons  of  sugar  of  a  present  value  of  nearly 
$8,000,000. 

Investigation  has  shown  that  a  grape  syrup  can  be  made  which  is 
wholesome,  attractive,  and  suitable  for  table  use,  cooking,  the  making 
of  jams,  and  fruit  butters,  and  for  the  canning  of  most  of  our  fruits. 

Most  of  the  equipment  necessary  for  making  this  syrup  already 
exists  in  the  wineries  and  beet-sugar  factories  of  the  state  and  what 
is  lacking  could  be  easily  obtained. 

The  marketing  of  this  large  quantity  of  a  new  product  could  be 
successfully  done  only  if  many  fruit  canneries  could  be  induced  to 
use  a  certain  quantity  of  grape  syrup  during  the  season  of  1920. 
This  could  probably  be  done  only  by  suitable  governmental  regulation. 


STATION  PUBLICATIONS   AVAILABLE   FOR   FREE   DISTRIBUTION 


No. 
230 
250 
251, 


BULLETINS 

No. 

277. 
278. 
279. 
280. 


Enological  Investigations. 

The  Loquat. 

Utilization  of  the  Nitrogen  and  Organic 

Matter   in    Septic    and    Imhoff   Tank 

Sludges. 
Deterioration  of  Lumber.  281. 

Irrigation   and   Soil   Conditions   in  the 

Sierra  Nevada  Foothills,  California.  282. 

The  Citricola  Scale. 

New  Dosage  Tables.  283. 

Melaxuma    of    the    Walnut,     "Juglans  284. 

regia."  286. 

Citrus   Diseases   of   Florida   and   Cuba  288. 

Compared  with  Those  of  California. 
Size  Grades  for  Ripe  Olives.  290. 

264.  The  Calibration  of  the  Leakage  Meter. 

265.  Cottonv  Rot  of  Lemons  in   California.  291. 

266.  A  Spotting  of  Citrus  Fruits  Due  to  the 

Action  of  Oil  Liberated  from  the  Rind.  292. 

Experiments  with  Stocks  for  Citrus. 

Growing  and  Grafting  Olive  Seedlings.  293. 

A  Comparison  of  Annual  Cropping,  Bi-  294. 

ennial  Cropping,  and  Green  Manures  295. 

on  the  Yield  of  Wheat.  296. 

Feeding  Dairy  Calves  in  California.  297. 

Commercial  Fertilizers.  298. 

Preliminary  Report  on  Kearney  Vine-  299. 

yard  Experimental  Drain. 

The  Common  Honey  Bee  as  an  Agent  300. 

in  Prune  Pollination.  301. 

The  Cultivation  of  Belladonna  in  Cali- 
fornia. 302, 

The  Pomegranate.  303, 


252. 
253. 

255. 
257. 
261. 

262. 

263. 


267. 
268. 
270. 


271. 
272. 
273. 

274. 

275. 

276. 


Sudan  Grass. 

Grain  Sorghums. 

Irrigation  of  Rice  in  California. 

Irrigation  of  Alfalfa  in  the  Sacramento 
Valley. 

Control  of  the  Pocket  Gophers  in  Cali- 
fornia. 

Trials  with  California  Silage  Crops  for 
Dairy  Cows. 

The  Olive  Insects  of  California. 

Irrigation  of  Alfalfa  in  Imperial  Valley. 

Commercial  Fertilizers. 

Potash  from  Tule  and  the  Fertilizer 
Value  of  Certain  Marsh  Plants. 

The  June  Drop  of  Washington  Navel 
Oranges. 

The  Common  Honey  Bee  as  an  Agent 
in  Prune  Pollination.     (2nd  report.) 

Green  Manure  Crops  in  Southern  Cali- 
fornia. 

Sweet  Sorghums  for  Forage. 

Bean  Culture  in  California. 

Fire  Protection  for  Grain  Fields. 

Topping  and  Pinching  Vines. 

The  Almond  in   California. 

The  Seedless  Raisin  Grapes. 

The  Use  of  Lumber  on  California 
Farms. 

Commercial  Fertilizers. 

California  State  Dairy  Cow  Competi- 
tion,  1916-18. 

Control  of   Ground   Squirrel. 

Grape  Syrup. 


No. 
113. 
114. 
115. 
124. 
126. 
127. 
128. 
129. 
131. 
133. 
135. 
136. 
137. 
138. 
139. 


142. 
143. 

144. 

147. 
148. 
150. 
151. 
152. 

153. 

154. 


155. 
156. 
157. 
158. 
160. 
161. 
162. 

164. 
165. 


CIRCULARS 
No. 

Correspondence  Courses  in  Agriculture.  166. 

Increasing  the  Duty  of  Water.  167. 

Grafting  Vinifera  Vineyards.  168. 
Alfalfa   Silage  for  Fattening  Steers. 

Spraying  for  the  Grape  Leaf  Hopper.  169. 

House  Fumigation.  170. 
Insecticide  Formulas. 

The  Control  of  Citrus  Insects.  172. 

Spraying  for  Control  of  Walnut  Aphis.  174. 

County  Farm  Adviser.  175. 
Official  Tests  of  Dairy  Cows. 

Melilotus  Indica.  176. 
Wood  Decay  in  Orchard  Trees 

The  Silo  in   California  Agriculture  177. 

The    Generation    of   Hydrocyanic   Acid  179. 

Gas  in   Fumigation   by   Portable   Ma- 
chines. 181. 
The  Practical  Application  of  Improved 

Methods  of  Fermentation  in   Califor-  182. 

nia  Wineries  during  1913  and  1914. 

Practical  and  Inexpensive  Poultry  Ap  183. 

pliances.  184. 

Control    of    Grasshoppers    in    Imperial  185. 

Valley. 

Oidium  or  Powderv  Mildew  of  the  Vine  186. 

Tomato  Growing  in  California.  187. 

"Lungworms."  188. 

Round  Worms  in  Poultrv.  189. 

Feedine  and  Management  of  Hojrs  191. 

Some  Observations  on  the  Bulk  Hand  193. 

ling  of  Grain   in  California.  196. 

Announcement  of  the  California   State  197. 

Dairv  Cow  Competition.    1916-18. 

Irrigation   Practice   in   Growing   Small  198. 

Fruits  in  California.  199. 

Bovine  Tuberculosis.  200. 
How  to  Operate  an  Incubator. 

Control  of  the  Penr  Scab.  201. 

Home  and  Farm  Canning.  202. 
Lettuce  Growing  in  California. 

Potatoes  in   California.  203. 

White    Diarrhoea    and    Coccidiosis    of  20A. 

Chicks.  205. 

Small  Fruit  Culture  in  California.  206. 
Fundamentals    of    Sugar    Beets    under 

California   Conditions. 


The  County  Farm  Bureau. 

Feeding  Stuffs  of  Minor  Importance. 

Spraying  for  the  Control  of  Wild  Morn- 

ing-Glory  within  the  Fog  Belt. 
The  1918  Grain  Crop. 
Fertilizing     California     Soils     for     the 

1918  Crop. 
Wheat  Culture. 
Farm  Drainage  Methods. 
Progress  Report  on  the  Marketing  and 

Distribution  of  Milk. 
Hog     Cholera      Prevention      and     the 

Serum  Treatment. 
Grain  Sorghums. 
Factors    of    Importance    in    Producing 

Milk  of  Low  Bacterial  Count. 
Control     of     the     California     Ground 

Squirrel. 
Extending  the  Area  of  Irrigated  Wheat 

in  California  for  1918. 
Infectious  Abortion  in  Cows. 
A  Flock  of  Sheep  on  the  Farm. 
Beekeeping  for  the  Fruit-Grower  and 

Small  Rancher,  or  Amateur. 
Poultry  on  the  Farm. 
Utilizing  the  Sorghums. 
Lambing  Sheds. 
Winter  Forage  Crops. 
Pruning  the  Seedless  Grapes. 
A  Study  of  Farm  Labor  in  California. 
Dairy  Calves  for  Veal. 
Suggestions   for   Increasing   Egg   Pro- 
duction in  a  Time  of  High-Feed  Prices. 
Syrup  from  Sweet  Sorghum. 
Onion  Growing  in  California. 
Growing  the   Fall   or   Second   Crop   of 

Potatoes  in  California. 
Helpful  Hints  to  Hog  Raisers. 
County    Organization    for    Rural    Fire 

Control. 
Peat  as  a  Manure  Substitute. 
Handbook  of  Insect  Pests. 
Blackleg. 
Jack  Cheese. 


